Blower and ventilation system

ABSTRACT

Provided is a blower installed at a manhole opening, with which it is possible to facilitate an entry or an exit of a worker or an import or an export of an article. The present invention provides a ventilation system comprising a frame and a single or a plurality of airflow generation means arranged at the frame, a direction of an airflow is adjusted so that the airflow generated from the airflow generation means flows along with a virtual axis penetrating a virtual surface which the frame is regarded as to periphery, and the airflow flows while swallowing up the surrounding air of the virtual axis, and an air volume more than two times of total fluid volume of the airflow is generated.

This is a Continuation of application Ser. No. 15/535,679, filed Jun.13, 2017, which in turn is a National Phase Application ofPCT/JP2015/084408, filed Dec. 8, 2015, which claims the benefit ofJapanese Patent Application No. 2014-252550, filed Dec. 13, 2014. Thedisclosure of each of the prior applications is hereby incorporated byreference herein in its entirety.

TECHNICAL FIELD

The present invention relates to a blower and a ventilation system. Inparticular, the present invention relates to a blower and a ventilationsystem preferably applied for ventilation in a structure, such as a pipeconduit, a pipe line or tunnel which is installed on and under theground.

BACKGROUND ART

In a pipe conduit or a pipe line of sewerage (hereinafter, simplyreferred to as “pipe conduit”), when a manual work such as a maintenanceand inspection is carried out, a worker generally enters from a manholeinto a pipe conduit. In the pipe conduit, a worker may be in an oxygendeficiency state, and a poisonous gas such as hydrogen sulfide may begenerated, and thus, it is needed to ensure safety management for aworker staying in the pipe conduit.

Non Patent Literature 1 is a report on a safety in work within a sewerpipe conduit and provides recommendations and specific safety issuesbased on analysis of an accident case. In particular, on page 27 of theNon Patent Literature 1, a method of ventilating inside pipe conduit isdescribed in which “a fan is installed in consideration of a winddirection of an outer air, and the air is blown from one direction andthe air is exhausted to outside from another direction thereby to carryout a ventilation in the pipe conduit. The wind speed in the pipeconduit at this time should be over 0.8 m/second.” The Literatureillustrates an image of a cleaning work, and provides also an example ofa fan and a duct by way of photo. According to the image of the cleaningwork, ducts are inserted into both manholes at an air-blow side and anair-exhaust side, and the air is blown and exhausted by the fanconnected to a ground surface side of each duct.

When ventilation is carried out in the structure for the purpose ofsecuring a traffic route such as a tunnel, for example, there is adopteda ventilation method that the fan is installed on a ceiling part of thestructure, an airflow is generated in the structure and ventilation isachieved in the structure by intake and exhaust of the airflow from anentrance.

It is noted that Patent Literature 1 discloses an air intake and exhaustdevice for a manhole and Patent Literature 2 discloses a ventilationdevice for an underground structure.

CITATION LIST Patent Literature

[PTL 1] Japanese Unexamined Patent Application Publication No.2000-104966

[PTL 2] Japanese Unexamined Patent Application Publication No.2003-328378

Non Patent Literature

[NPL 1] “Intermediate report on safety management on work within sewerpipe conduit”, Sewer Pipe Conduit Work Safety Management Committee,April, 2002 (http://jascoma.com/siryou/k_200804_cyukanhoukoku.pdf)

SUMMARY OF INVENTION Technical Problem

When the fan and the ducts are applied to the manhole as stated in the“image of a cleaning work” described in Non Patent Literature 1 so thatthe air is blown and exhausted, it is possible to ensure the safety of aworker and it is needed to do so in order to ensure safety in work. Onthe other hand, a duct inserted into the manhole blocks the manholeopening, and when the duct is inserted into the manhole, it isinconvenient to make an entry or an exit of a worker and an import or anexport of a component. Further, when there is no space for an entry oran exit of a person or for an import or an export of an article betweenthe manhole opening and the duct, it is needed to remove the duct fromthe manhole, resulting in a situation where the air needs be temporarilystopped from being blown or exhausted, hence not preferable for thesafety management. Further, when an emergency such as a generation ofpoisonous gas occurs in the middle of a work in the pipe conduit, it isneeded to immediately evacuate the worker from the pipe conduit.

Furthermore, when means for installing the fan on a ceiling part isadopted for ventilation of the structure for the purpose of securing atraffic route such as a tunnel, space is needed for installation of thefan, sectional area of the structure is increased more than thatnecessary for the traffic route, therefore cost may be increased forconstruction of the structure. Furthermore, the tunnel as the structurefor securing the traffic route should not intersect the traffic at anentrance and an exit. A ventilation means is required which does notintersect the traffic at the entrance and the exit.

An object of the present invention is to provide a preferable blowerinstalled on a manhole opening, with which it is possible to facilitatean entry or an exit of a worker or an import or an export of an article.Further, an object of the present invention is to provide a blowerinstallable at an entrance and an exit without intersectingtransportation of a structure such as a tunnel. Additionally, an objectof the present invention is to provide a ventilation system using theblower in a pipe conduit or the structure such as the tunnel.

Solution to Problem

To resolve the above-described problem, according to a first aspect ofthe present invention, there is provided a blower comprising a frame anda single or a plurality of airflow generation means arranged at saidframe, wherein a direction of an airflow is adjusted so that saidairflow generated from said airflow generation means flows along with avirtual axis penetrating a virtual surface which said frame is regardedas periphery, and said airflow flows while swallowing up the surroundingair of said virtual axis, and an air volume more than two times of totalfluid volume of said airflow is generated.

Said virtual axis vertically may intersect said virtual surface at acenter point of the same. Said plurality of airflow generation means maybe arranged at said frame, and a direction of each airflows may beadjusted so that each airflow generated by said plurality of airflowgeneration means flows toward one point on said virtual axis. Saidplurality of airflow generation means may be arranged at a symmetricposition having a center which is an intersection point of said virtualsurface and said virtual axis. A blower may comprise an installationtool for installing said airflow generation means on said frame, whereinsaid installation tool may include an angle adjustment mechanism foradjusting an angle of said airflow generation means against said virtualsurface. An incident angle of said airflow against said virtual surfacemay be preferable as 16 to 24 degrees. Said airflow generation means maycomprise a generation source of said airflow and injection nozzles forinjecting said airflow, and said each injection nozzle may comprise aconical part for converging the airflow sent from said generationsource, and a cylindrical part positioned at a top end of said conicalpart. Said injection nozzle may comprise a direction adjustmentmechanism for adjusting a direction of said airflow. A blower maycomprise a fixing tool for fixing said frame to the manhole opening. Ablower may comprise a blockage member for blocking a gap between acircumferential area of the manhole opening and said frame. A blower maycomprise an airflow reflection member which is installed at the manholeopening, is flexible member dropping to a lower part in the manhole, andconverts a direction of airflow from a vertical direction to ahorizontal direction. A blower may comprises an additive supplying meansfor supplying one or more additives selected among an aromatic, water orsteam to an air inflowed into said airflow generation means.

According to a second aspect of the present invention, there is provideda ventilation system using the above-mentioned blower, wherein saidblower is installed in an entrance or an exit of a pipe conduit, a pipeline or a path, or at least one of an entrance, an exit or a manhole ofa manhole connected to the pipe conduit or the pipe line, or themanhole.

A ventilation system may comprise an airflow direction conversion meansfor converting a direction of the airflow from a vertical direction to ahorizontal direction, or from the horizontal direction to the verticaldirection at an entrance or an exit to which said blower is installed,or at a bottom of the manhole. Said airflow direction conversion meansmay be an airflow reflection plate for converting a direction byreflecting said airflow. Said airflow direction conversion means maycomprise a second airflow generation means for generating a secondairflow different from the airflow from said blower, and said secondairflow is joined in a different direction from the airflow from saidblower and the direction of said airflow is converted. An exhaust devicemay be installed on at least one of an entrance, an exit or a manholewhich is different from an entrance, an exit or a manhole on which saidblower is installed. Said exhaust device may be preferably installed ona first entrance, exit or manhole which are located downstream relativeto the entrance, the exit or the manhole on which said blower isinstalled. The ventilation system may comprise an airflow directionconversion means for converting a direction of the airflow from avertical direction to a horizontal direction, or from the horizontaldirection to the vertical direction at an entrance, an exit or a bottomof a manhole to which said exhaust device is installed.

It is noted that the above-described Summary of Invention does not listall the characteristics necessary for the present invention. Further, asubcombination of these groups of characteristics may be invention.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a cross-sectional view showing an example of a ventilationsystem of a sewer pipe conduit.

FIG. 2 is a cross-sectional view showing an example of a blower 140arranged at a manhole opening.

FIG. 3 is a top view showing an example of a blower 140 arranged at amanhole opening.

FIG. 4 is a schematic view showing an example of an airflow generationmeans 144.

FIG. 5 is a cross-sectional view showing another example of aventilation system of a sewer pipe conduit.

FIG. 6 is a cross-sectional view showing a variation of a ventilationsystem 200.

FIG. 7 is a cross-sectional view showing another variation of aventilation system 200.

FIG. 8 is a cross-sectional view showing yet another example of aventilation system of a sewer pipe conduit.

FIG. 9 is a cross-sectional view showing still yet another example of aventilation system of a sewer pipe conduit.

FIG. 10 is a cross-sectional view showing another example of a blower140 arranged at a manhole opening.

FIG. 11 is a cross-sectional view showing yet another example of aventilation system of a sewer pipe conduit.

DESCRIPTION OF EMBODIMENTS

Hereinafter, the present invention will be described by way of anembodiment of the present invention, however, an embodiment that followsis not limiting the invention as set forth in the scope of claims.Further, all the combinations of characteristics described in theembodiment are not necessary essential for the means for solving theinvention.

FIG. 1 is a cross-sectional view showing an example of a ventilationsystem of a sewer pipe conduit. A ventilation system 100 ventilates apipe conduit 110 buried beneath a ground surface 102. The pipe conduit110 is an underground space divided by a bottom 114 and a wall surface112, and includes a cross-sectional surface having a shape of ahorseshoe. Between the pipe conduit 110 and the ground surface 102, amanhole 116 and a manhole 118 are arranged, and a worker is capable ofentering the pipe conduit 110 through the manhole 116 or the manhole118. In the present embodiment, description proceeds with a case wherethe pipe conduit 110 between the manhole 116 and the manhole 118 isventilated. The manhole 116 is at an air-blow side and the manhole 118is at an air-exhaust side. In this case, description proceeds with acase where the manhole 116 and the manhole 118 are adjacent to eachother, however, the manhole 116 and the manhole 118 need not be adjacentto each other. In order to shield a pipe conduit region between themanhole 116 and the manhole 118 from another pipe conduit region, ashield curtain 120 may be arranged in the pipe conduit 110. The shieldcurtain is efficient in ventilation.

A blower 140 is installed at an opening of the manhole 116 at theair-blow side, and an exhaust device 170 is installed at the manhole 118at the air-exhaust side. The exhaust device 170 is a conventionalfan-type exhaust device, and a duct 172 connected to the exhaust device170 is inserted into the manhole 118. It is noted that the blower 140may be installed at a plurality of manholes, and the exhaust device 170may be installed at a plurality of manholes. Further, the manhole 118 ispreferably the first manhole on downstream side of the manhole 116. Whenthe blower 140 is installed on upstream side and the exhaust device 170is installed on downstream side, it is possible to blow air along a flowof sewage. Further, when the blower 140 and the exhaust device 170 areinstalled between the adjacent manholes, it is possible to shorten adistance between the air-blow and the air-exhaust, resulting in a goodventilation efficiency.

FIG. 2 is a cross-sectional view showing an example of the blower 140installed in a manhole opening 116 b, and FIG. 3 is a top view thereof.Reference numeral 116 a shows a manhole inner wall, and a worker can goin and out of the manhole 116 by using lifting metal fittings (notshown).

The blower 140 has a frame 143 and an airflow generation means 144, andthe plurality of airflow generation means 144 are arranged along theframe 143.

The frame 143 is, for example, formed with metals, and has a ring-likeshape. The shape of the frame 143 is not limited. An outer appearance ofthe frame 143 may have a ring-like or circular arc-like outer appearancecorresponding to a shape of a manhole opening 116 b, however, it is notlimited thereto. The shape of the frame 143 may have a polygon, such asa triangle, a square, and a hexagon, an oval shape, and a shape ofhorseshoe.

The airflow generation means 144 generates an airflow 145 in thedirection of the arrow as shown in figures. As the airflow generationmeans 144. a blower having an electric fan can be illustrated.Alternatively, as the airflow generation means 144, a DC fan can beillustrated. The airflow generation means 144 is not limited to theelectric fan or the DC fan, and has only to generate the airflow.

FIG. 4 is a schematic view showing an example of the airflow generationmeans 144. The airflow generation means 144, for example, comprises ageneration source of the airflow and an injection nozzle for injectingthe airflow. As the generation source of the airflow, the DC fan 144 acan be illustrated, and the airflow is sent from an outgoing port 114 bof the DC fan 144 a. The injection nozzle comprises a conical part 144 cfor converging the airflow sent from the outgoing port 114 b and acylindrical part 144 d placed at end part of the conical part 144 c.Owing to the cylindrical part 144 d, a wind speed of the airflow ismaintained and turbulence of the airflow is suppressed.

A direction of airflow 145 is adjusted so that the airflow 145 generatedby the airflow generation means 144 flows along with a virtual axis 147penetrating a virtual surface 146 which the frame 143 is regarded asperiphery. In the blower 140 as shown in FIGS. 2 and 3, the virtual axis147 is a center line for vertically penetrating a center of the virtualsurface 146 which the frame 143 is regarded as periphery. By adjustingthe direction of the airflow 145 so that the airflow 145 flows alongwith the virtual axis 147, the airflow 145 flows while swallowing up thesurrounding air of the virtual axis 147, and there is generated an airvolume more than two times of total fluid volume of the airflow 145.

The airflow generation means 144 is installed at the frame 143 by aninstallation tool 148. The installation tool 148 may include an angleadjustment mechanism for adjusting the angle of the airflow generationmeans 144 relative to a disk surface of the frame 143 (the virtualsurface 146 which the frame 143 is regarded as periphery). Aninstallation angle of the airflow generation means 144 is adjusted bythe angle adjustment mechanism and each of the plurality of airflowgeneration means 144 can be arranged toward one point on a normal line(the virtual axis 147) positioned to the center of the disk surface ofthe frame 143. The airflow generation means 144 may comprise theinjection nozzle for injecting the airflow, and the injection nozzle mayadjust the direction of the airflow 145.

The installation tool 148 may include a clamp part for clamping theframe 143. In this case, it is possible that the clamp part makes theairflow generation means 144 detachable from the frame 143 and the angleof the airflow generation means 144 adjustable. Further, when theinstallation tool 148 includes the clamp part, the airflow generationmeans 144 becomes detachable from the frame 143, and therefore, theframes 143 having various sizes of diameters corresponding to themanholes having various sizes of opening diameters are prepared, and theframe 143 appropriate for the opening diameter of the manhole isselected and the airflow generation means 144 is attached by the clamppart to the selected frame 143. As a result, it is possible to easilycomply with manholes having various diameters.

In the present embodiment, the number of airflow generation means 144 isfour, and the four airflow generation means 144 are arranged at equalintervals along the frame 143. The number of airflow generation means144 is not limited to four, and at least two or more airflow generationmeans may suffice. However, in consideration of efficiency of air blow,the number of airflow generation means 144 is preferably more thanthree. The more the airflow generation means, the better the efficiencyof the air blow, however, an unnecessary large number of airflowgeneration means may result in a cost increase. Therefore, the number ofairflow generation means 144 is preferably decided on the basis of thebalance between the air-blow efficiency and the cost. The plurality ofairflow generation means 144 is preferably disposed on a symmetricposition having a center which is an intersection point of the virtualsurface 146 and the virtual axis 147.

The frame 143 may be configured by a plurality of members. In this case,when transported, the frame 143 may be separate in a plurality ofmembers. The frame 143 may be folded so that the plurality of membersare piled each other. Furthermore, a fixing tool for fixing the frame143 at the manhole opening 116 b may be included. When the blower 140 isfixed at the manhole opening, it is possible to increase the safetylevel.

EXAMPLE 1

Table 1 shows a result of an experience by measuring an air volume,where a blower 140 is installed at one end of a pipe having an innerdiameter of 600 mm and a length of 2 m, and at another end of the pipe,the air volume is measured.

TABLE 1 experimental experimental experimental experimental experimentalexperimental comparative example 1 example 2 example 3 example 4 example5 example 6 example 1 discharge diameter 24 24 24 24 24 24 300 (mm)number of discharge port 2 2 3 3 4 4 1 power supply (W) 1000 650 1440970 1820 1240 550 discharge air volume 4.6 2.4 6.9 3.5 9.2 4.5 35.9(m³/min) pipe exit air volume 77 67 100 77 127 86 59 (m³/min)multiplication constant 16.7 27.9 14.5 22 13.8 19.1 1.6 (times)

Experimental examples Nos. 1 to 6 are cases that the blower 140 isapplied, and a comparative example No. 1 is a case that the conventionalfan and duct are applied. In the experimental examples Nos. 1 to 6, theairflow generation means 144 is an electric blower having a dischargediameter of 24 mm. In the experimental examples Nos. 1 to 6, there arechanges in the number of discharge ports and the number of the electricblowers within the range of 2 to 4, and power supply (total volume) tothe electric blower is also changed within a range of 650 W to 1820 W.Total air volume at the discharge port (discharge air volume) of theelectric blower is equal to a total volume of the airflow 145 at theblower 140 and is shown in Table 1. The air volume (pipe exit airvolume) at another end (exit) of the pipe is, as shown in Table 1, morethan two times of the discharge air volume (total volume of the airflow145) in the experimental examples Nos. 1 to 6, and multiplicationconstant (pipe exit air volume/discharge air volume) becomes largerwithin a range of 13.8 to 27.9. This is because the airflow 145 isadjusted so as to flow along with the virtual axis, while swallowing upthe surrounding air of the virtual axis. As a result, a large volume ofair more than the total volume of the airflow 145 is sent out. On theother hand, in the comparative example, multiplication constant is equalto 1.6, and effect such in the present invention has not been found.

EXAMPLE 2

A length of nozzle of the airflow generation means was changed within arange of 100 mm to 300 mm, and diameters of the nozzles were changedwithin a range of 30 mm to 50 mm. As a result, the maximum dischargewind speed 27 m/s is obtained when the length of the nozzle is 100 mmand the diameter of the nozzle is 100 mm. However, when the length ofthe nozzle is 100 mm and the diameter of the nozzle is 40 mm, turbulenceof the airflow at the discharge port of the nozzle became large. Takingthese into consideration, a nozzle was prepared which has a length of aconical part of 100 mm, a length of a cylindrical part of 50 mm, and ashape of a cylinder is added to a top end of the cone. This nozzlemaintains the maximum wind speed 27 m/s at the discharge port andturbulence of the airflow was not found.

EXAMPLE 3

Table 2 shows a result of an experience by measuring an average windspeed and air volume, where two airflow generation means 144 areinstalled with different angles at one end of a pipe having an innerdiameter of 600 mm and a length of 2 m, and at another end of the pipe,the average wind speed and the air volume are measured.

TABLE 2 experimental experimental experimental experimental experimentalexperimental experimental experimental example 7 example 8 example 9example 10 example 11 example 12 example 13 example 14 focal position(m) 0.50 0.70 0.75 0.80 1.00 1.25 1.50 2.00 pipe exit average 2.42 2.552.54 2.50 2.51 2.37 2.26 2.25 wind speed (m/s) pipe exit air volume39.64 41.75 41.71 41.04 41.17 38.91 37.02 36.90 (m³/min)

Preferable air quantities are obtained in experimental examples No. 8(focal position being 0.70 m) to No. 11 (focal position being 1.00 m). Arange of the focal position falls within 16.7 to 23.2 degrees of anincident angle against a cross-section of the pipe of the airflowdischarged from the nozzle. It becomes apparent that preferable pipeexit air volume can be obtained when the angle against the cross-sectionof the pipe of the nozzle becomes 16 to 24 degrees.

EXAMPLE 4

Table 3 shows a result of an experience by measuring an average windspeed and air volume, where the number and arrangement of airflowgeneration means 144 of the Example 2, and an output of a a generationsource of the airflow (the discharge wind speed) are changed, and atanother end of the pipe, the average wind speed and the air volume aremeasured. In Table 3, item of “an arrangement of nozzles” means aposition of each nozzle on the frame 143 of the airflow generation means144. In experimental examples 15, 17 and 19, the airflow generationmeans 144 are arranged in a manner of three-fold symmetry, four-foldsymmetry and six-fold symmetry against each of the virtual axis 147. Onthe other hand, experimental examples 16, 18 and 20 show experimentalexamples having axial symmetry lower than that of the experimentalexamples 15, 17 and 19. An angle (only an acute angle) made by eachairflow generation means 144 becomes 30 degrees in the experimentalexample 16, 40 degrees in the experimental example 18, and 40 and 50degrees in experimental example 20. Nozzle arrangement of theexperimental examples 21 and 23 is equal to that of the experimentalexamples 18 and 20. An angle (only an acute angle) made by each airflowgeneration means 144 of the experimental example 22 becomes 73 degrees.

TABLE 3 experi- experi- experi- experi- mental mental experimentalexperimental experimental experimental experimental mental mentalexample example example example example example example example example15 16 17 18 19 20 21 22 23 number 3 3 4 4 6 6 4 4 6 of discharge port(number of nozzle) discharge 27 27 27 27 27 27 31 31 31 wind speed (m/s)nozzle arrange- ment

pipe exit 3.18 2.53 3.62 3.40 4.34 4.58 4.47 4.47 5.33 average windspeed (m/s) pipe exit 52.09 41.45 59.37 55.72 71.18 75.06 73.24 73.2487.44 air volume (m³/min)

It becomes apparent that preferable pipe exit air quantities areobtained in comparison with the experimental examples 15, 16, 17 and 18when the nozzle arrangement is made as symmetry against a center axis.The larger the number of the airflow generation means 144 (the number ofnozzles) and the larger an output of the generation source of theairflow (discharge wind speed), it becomes apparent that the preferablepipe exit air volume is obtained. In the experimental example 23,practically enough pipe exit air volume (87.44 m³/min) was obtained. Incomparison with experimental examples 21 and 22, the experimentalexample 21 is higher in symmetry of the nozzle arrangement than that ofthe experimental example 22. On the other hand, considering a case aworker moves up and down with holding the frame 143 by a hand, thenozzle arrangement of the experimental example 22 is preferable due tono difficulty to hold the frame 143. In this case, the nozzlearrangement of the experimental example 22 may be applied, taking easeof moving up and down of the worker into consideration, rather thanpriority of the symmetry of the nozzle arrangement.

As described above, according to the ventilation system 100 of thepresent invention, it is possible to obtain the wind speed equivalent toor more than the conventional ventilation system. In addition, theblower 140 of the present ventilation system 100 is different from theconventional fan-type blower and does not need a flexible duct. Thus, itis possible to make the blower smaller in size. Further, in the blower140 of the present invention, the manhole opening is not blocked as theconventional blower, so that an entry or an exit of a worker and animport or an export of an article are facilitated, and it is notnecessary to stop the operation of the blower 140 during importation orexportation. Moreover, it is possible to ensure an escape route inemergency, and possible to further increase the safety of a worker.

Thus, the present invention is described by using an embodiment;however, the technical scope of the present invention is not limited tothe scope of the above-described embodiment. It is evident to thoseskilled in the art that various modifications or improvements can beadded to the embodiment above. It is also evident, based on therecitation of the claims, that the aspects to which the variousmodifications or improvements have been added may be also included inthe technical scope of the present invention.

For example, FIG. 5 is a cross-sectional view showing another example ofthe ventilation system of the sewer pipe conduit. In a ventilationsystem 200 shown in FIG. 5, an airflow reflection plate 202 forconverting a direction of airflow from a vertical direction to ahorizontal direction or from a horizontal direction to a verticaldirection is installed at a bottom of either one or both of the manhole116 in which the blower 140 is installed and the manhole 118 in whichthe exhaust device 170 is installed. Such an airflow reflection plate202 regulates a flow of air and reduces energy loss of an airflowgenerated when the direction of the flow of air is changed to achieve amore smooth flow, and as a result of which it is possible to increasethe flow speed and the air volume in the pipe conduit 110.

As the airflow direction converting means, as shown in FIG. 6, a secondairflow generation means 204 may be used. As the second airflowgeneration means 204, a normal fan-type blower can be illustrated. Thesecond airflow generation means 204 generates a second airflow 206different from the airflow from the blower 140, and the second airflow206 is joined from a direction different from that of the airflow fromthe blower. The direction of the airflow is converted thereby. As shownin FIG. 7, instead of the second airflow generation means 204, the samemeans as the airflow generation means 144 may be used.

Further, FIG. 8 is a cross-sectional view showing yet another example ofa ventilation system of a sewer pipe conduit. In a ventilation system300 shown in FIG. 8, the blower 140 of the present invention isinstalled at the manhole 116 at the air-blow side, and in addition, ablower 340 equivalent to the blower 140 of the present invention isinstalled at the manhole 118 at the air-exhaust side. According to theventilation system 300, the blower 340 of the present invention isinstalled also at the manhole 118 at the air-exhaust side, so thatexhaust performance is improved, an entry or an exit of a worker and animport or an export of an article are further facilitated, and it ispossible to further increase the safety of a worker while ensuring aplurality of escape routes in emergency.

Further, FIG. 9 is a cross-sectional view showing still yet anotherexample of a ventilation system of a sewer pipe conduit. A ventilationsystem 400 shown in FIG. 9 is provided with a booster 402 in the pipeconduit 110. In the booster 402, a blower equivalent to the blowers 140and 340 is provided. The booster 402 generates the airflow in adirection to accelerate a flow in the pipe conduit 110. According to theventilation system 400, the airflow in the pipe conduit 110 is bolsteredby the booster 402, and thus, it is possible to further increase thesafety of a worker. It is noted that in the ventilation system 400,instead of the exhaust device 170 and the duct 172, the blower 340 maybe installed at the manhole 118 at the air-exhaust side as in theventilation system 300.

In the above-described embodiment as the blower 140, an example isdescribed in which the airflow generation means 144 having a cylindricalflow channel is arranged discontinuously along the frame 143; however,an opening of the nozzle may be arranged sequentially or continuouslyalong the frame. For example, a nozzle having a slit-like opening isadopted, an air is supplied to a flow channel connected to the slit-likeopening, the air is emitted in a normal direction of a disk surface ofwhich the circumference is a frame, and the air is emitted whileswallowing up the surrounding air. In this way, the airflow may begenerated in the normal direction of the disk surface. The slit-likenozzle in this case may be formed with an opening continuously allacross the entire frame, and in a slit-like nozzle having an openingwith an appropriate length, the opening may be arranged continuouslyalong the frame.

In the above-described embodiment, an example is described that theframe 143 suitable for the diameter of the manhole opening 116 b isapplied, however, as shown in FIG. 10, a blockage member 502 and theframe 143 having a diameter smaller than the diameter of the manholeopening 116 b may be applied to the manhole 116 having a larger opening.The blockage member 502 is to block a gap between a circumferential areaof the manhole opening 116 b and the frame 143, and is capable of makingthe frame 143 suitable for the manhole opening 116 b having a largerdiameter.

Further, as shown in FIG. 11, the blower 140 may include an airflowreflection member 602. The airflow reflection member 602 is a flexiblemember such as nylon, for example, and converts the direction of airflow from a vertical direction to a horizontal direction. The airflowreflection member 602 installed on the manhole opening 116 b is dropped,by a rope member 604, for example, to a lower part in the manhole 116.

When folded back, the airflow reflection member 602 and the rope member604 can be stored in a compact manner, and convenient to simply expandby being installed at the manhole opening 116 b and then dropped, henceconvenient.

Further, in the above-described embodiment, an additive supplying meansfor supplying the one or more additives selected among an aromatic,water or steam to an air inflowed into the airflow generation means 144.As the additive supplying means, it has only to put the aromatic, thewater or the steam at the entrance of airflow. By supplying thearomatic, it is possible to inform a worker working in the pipe conduit110 to that the air is normally supplied. Furthermore, by supplying thewater and the steam, it is possible to protect the worker working in thepipe conduit 110 from drying.

In the above-described embodiment, description is made about an examplethat the blower and the ventilation system are applied to mainly themanhole and the underground pipe conduit, however, it is not necessarythe pipe conduit arranged underground, and the present invention isapplied to the pipe conduit and a pipe line installed on the ground. Inaddition, the above-described blower and ventilation system can beapplied to the structure which should not intersect the traffic at theentrance and the exit of the tunnel. When the blower and the ventilationsystem according to the present invention are applied to the tunnel, itis not necessary to install an additional blower on the ceiling forventilation and the structure of the tunnel can be made small and costfor construction can be suppressed.

1. A blower comprising: a frame; a single or a plurality of airflowgeneration fans arranged at said frame; and an installation toolconfigured to install said airflow generation fan or fans on said frame,wherein a direction of an airflow is adjusted so that said airflowgenerated from said airflow generation fan or fans flows along with avirtual axis penetrating a virtual surface which said frame is regardedas periphery, said airflow flows while swallowing up the surrounding airof said virtual axis, and an air volume more than two times of totalfluid volume of said airflow is generated, and said installation tool isconfigured to adjust an angle of said airflow generation fan or fansagainst said virtual surface such that an incident angle of said airflowagainst said virtual surface becomes 16 to 24 degrees.
 2. A bloweraccording to claim 1, wherein said virtual axis vertically intersectssaid virtual surface at a center point of the same.
 3. A bloweraccording to claim 1, wherein said plurality of airflow generation fansare arranged at said frame, and a direction of each airflow is adjustedso that each airflow generated by said plurality of airflow generationfans flows toward one point on said virtual axis.
 4. A blower accordingto claim 3, wherein said plurality of airflow generation fans arearranged at a symmetric position having a center which is anintersection point of said virtual surface and said virtual axis.
 5. Ablower according to claim 1, wherein said airflow generation fan or fanscomprise a generation source and an injection nozzle having a conicalpart for converging the airflow sent from said generation source, and acylindrical part positioned at a top end of said conical part.
 6. Ablower according to claim 5, wherein said injection nozzle is configuredto adjust a direction of said airflow.
 7. A blower according to claim 1,further comprising a blockage member for blocking a gap between acircumferential area of a manhole opening and said frame.
 8. A bloweraccording to claim 1, further comprising an airflow reflection platewhich is installed through a manhole opening, the airflow reflectionplate being positioned in a lower part in a manhole to convert adirection of airflow from a vertical direction to a horizontaldirection.
 9. A ventilation system using the blower according to claim1, wherein said blower is installed in an entrance or an exit of a pipeconduit, a pipe line or a path, or at least one of an entrance and anexit of a manhole connected to the pipe conduit or the pipe line, or themanhole.
 10. A ventilation system according to claim 9, furthercomprising an airflow direction conversion plate for converting adirection of the airflow from a vertical direction to a horizontaldirection, or from the horizontal direction to the vertical direction,at an entrance or an exit to which said blower is installed, or at abottom of the manhole.
 11. A ventilation system according to claim 9,further comprising an airflow direction conversion fan for generating asecond airflow different from the airflow from said blower, and saidsecond airflow is joined in a different direction from the airflow fromsaid blower and the direction of said airflow is converted.
 12. Aventilation system according to claim 9, wherein an exhaust fan isinstalled on at least one of an entrance, an exit and a manhole which isdifferent from the entrance, the exit or the manhole on which saidblower is installed.
 13. A ventilation system according to claim 12,wherein said exhaust fan is installed on a first entrance, exit ormanhole which is located downstream relative to the entrance, the exitor the manhole on which said blower is installed.
 14. The ventilationsystem according to claim 12, further comprising an airflow directionconversion plate for converting a direction of the airflow from avertical direction to a horizontal direction, or from the horizontaldirection to the vertical direction, at the entrance, the exit or abottom of the manhole to which said exhaust fan is installed.